Spam is 'unsolicited advertising'.
That's the general/accepted terminology for the definition of spam.
On Stardock's skinning site - Wincustomize.com that excludes 'all' threads relating to skinning programs and their promotion, as they are specific to our 'game'.
Someone promoting their new Windowblinds skin release...whether a premium [paid-for] or freely released skin is NOT spam.
Someone linking to an off-site skinnable [such as the recent Gaia skin] is NOT spam. [its removal was due to other issues].
What 'appears' to be advertising, if it originates from legitimate sources [Stardock's Moderators/Admins] is also not spam. It is social communication to fellow members who may be interested and thus benefit from this communication.
No matter the source/origins what you see on the site will always be 'policed content', and typically verified for safety/security prior to its posting.
REAL spam is removed. as are its authors.
You, as a site member/contributor can feel safe that anything posted publicly is NOT detrimental to your well-being and/or site enjoyment.
That's why we are here...